Research has shown that chemical resistive-type sensors that utilize semiconducting nanoparticulates display relatively higher sensitivities and response rates over thin film sensors. Unfortunately, the ability to incorporate nanoparticulate semiconductors into a micro-platform, while maintaining the desired morphology, particle size, and composition, is challenging. In addition, there are few examples of microsensors utilizing nanomaterials for gas sensing at high-temperature (>500 degrees C). In this work, two refractory nanomaterial compositions, 10 vol% SnO2/90 vol% Gd1.8Y0.2Zr2O7 and Gd1.6Sm0.4Zr1.9Sn0.1O7, were deposited by a microcasting process to a thickness of similar to 100 mu m over DC-sputtered (and patterned) Zr + Pt composite electrodes. The interdigitated electrodes (IDEs) were shown to be stable up to 1200 degrees C for at least 15 h. The 10% SnO2/90% Gd1.8Y0.2Zr2O7 microsensor showed a 9.7% and 4.7% sensitivity at 600 and 1000 degrees C, respectively, to 4000 ppm of H-2 in N-2 (with a 20% 02). A nano-SnO2 microsensor had sensitivities of 81.2% and 1.0% at 600 and 1000 degrees C to 4000 ppm H-2 in 20% O-2/N-2. The response time for the microsensor at 600 degrees C showed a 63% greater sensitivity to 4000 ppm H-2 in N-2 compared to a traditional screenprinted sensor platform. The microsensor had 20 times the sensitivity compared to the screenprinted when tested in the same atmosphere. (C) 2013 The Electrochemical Society. All rights reserved.